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Results from the FRS Ion Catcher with projectile and fission fragments Timo Dickel GSI Helmholtzzentrum fr Schwerionenforschung, Darmstadt II. Physikalisches Institut, Justus-Liebig-Universitt Gieen, Germany Overview The FRS Ion

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SLIDE 1

NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Results from the FRS Ion Catcher with projectile and fission fragments

Timo Dickel

GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt

  • II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Germany
  • The FRS Ion Catcher a test facility for the LEB
  • Prototype of the Stopping Cell for the Super-FRS at FAIR
  • Multiple-Reflection Time-of-Flight Mass Spectrometer
  • Measurements at the FRS Ion Catcher in 2014
  • Conclusions and Outlook

Overview

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SLIDE 2
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Low Energy Branch of the Super-FRS at FAIR

LEB of the Super-FRS: universal and fast production - high selectivity - cooled exotic nuclei MATS (Precision Measurements of very short-lived nuclei

using an Advanced Trapping System for highly charged ions)

LaSpec (Laser Spectroscopy)

  • Eur. Phys. J. Special Topics 183 (2010) 1

MR-TOF MS Buncher / Degrader Stopping Cell

In-flight Production In-flight Separation Momentum Compression Stopping / Thermalization

Target Fragment Separator Primary Beam

100...1500 MeV/u ~ eV ~ keV ~ MeV/u Isobar Separation SuperFRS LEB Experiments (Trap, Laser,..) MATS / LaSpec

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SLIDE 3
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Stopping Cell Principle

Low-energy ion beam DC (+RF) DC+RF

RF structure: funnel or carpet High- energy ion beam

Dispersive Stage p+p p-p p p’ p’ p’ Monoenergetic Degrader Monoenergetic Ion Beam Ion Beam with Different Momenta p+p, p, p-p

Range Bunching Stopping Cell

  • H. Geissel et al., NIM A 282 (1989) 247
  • H. Weick et al., NIM B 164 (2000) 168
  • C. Scheidenberger et al., NIM B 204 (2003) 119
  • M. Wada et al., NIM B 204 (2003) 570
  • G. Savard et al., NIM B 2004 (2003) 582

Decreases range straggling by more than an order of magnitude  Enables stopping of ion produced at relativistic energies in gas-filled stopping cells Converts high energy, large emittance beam in low energy, low emittance beam

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SLIDE 4
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Stopping Cell Design

Cryogenic Operation Operate He-filled stopping cell at cryogenic temperature (~70 K)

  • Ultra-pure helium (freezing-out of contaminants)
  • Ideal for ion survival, 2+ charge state possible
  • No formation of molecules/adducts
  • Reduced radial ion diffusion
  • Reduced requirements for cleanliness  easier, more flexible construction

High-density Operation Use RF structure with small spacing to achieve high RF repelling field (PCB-based RF carpet instead of RF funnel)

  • High stopping gas densities
  • Less complex construction than RF funnels
  • P. Dendooven et al., NIM A 558 (2006) 580
  • S. Purushothaman et al., NIM B 266 (2008) 4488

Diameter: 250 mm Electrode spacing: 0.25 mm

  • M. Wada et al., NIM B 204 (2003) 570
  • M. Ranjan et al., Europhys. Lett. 96 (2011) 52001
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SLIDE 5
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Prototype of the Stopping Cell for the LEB

223Ra source

Extraction RFQ DC cage electrodes RF carpet

  • M. Ranjan et al., Europhys. Lett. 96 (2011) 52001.

W.R. Plaß et al., Nucl. Instrum. Methods B 317 (2013) 457.

  • M. Ranjan et al., Nucl. Instrum. Methods A 770 (2015) 87.

100 cm Outer chamber (room temperature) Insulation vacuum Exit hole

Developed in Collaboration

Inner chamber (cooling by cryo- cooler ~ 70 K)

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SLIDE 6
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Motivation: TOF Mass Spectrometry in Nuclear Physics

Enables high performance

  • Fast  access to very short-lived ions (T1/2 ~ ms)
  • Sensitive, broadband, non-scanning  efficient, access to rare ions

Conventional TOF-MS achieve medium mass resolving power only  Solution to achieve high mass resolving power and accuracy: Multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS)

  • H. Wollnik et al., Int. J. Mass Spectrom.

Ion Processes 96 (1990) 267

Applications in nuclear physics

  • Direct mass measurements of exotic nuclei
  • High-resolution isobar separator
  • Diagnostics measurements: Monitor production, separation and low-energy

beam preparation of exotic nuclei

  • C. Scheidenberger et al., Hyperfine Interact. 132 (2001) 531

W.R. Plaß et al., NIM B 266 (2008) 4560 W.R. Plaß et al., Int. J. Mass Spectrom. 394 (2013) 134 Ion source / injection trap Detector Analyzer

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SLIDE 7
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Multiple-Reflection Time-of-Flight Mass Spectrometer

Kinetic Energy 1.3 keV Ions Separated Ions Mass Measurement

2 m W.R. Plaß et al., Int. J. Mass Spectrom. 394 (2013) 134

  • T. Dickel et al., NIM A 777 (2015) 172 - 188
  • M. I. Yavor et al., IJMS (2015) in press

Full Mass Range, m/Δm ~ 103-104 m/Δm ~ 105-106, Mass Accuracy ~ 10-6-10-7 m/Δm > 105

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SLIDE 8
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Mass Measurement Accuracy Transmission efficiency Sensitivity Isobar separator with high ion capacity

100 200 300 400 500 1x10

5

2x10

5

3x10

5

4x10

5

5x10

5

Mass Resolving Power (FWHM) Number of Turns (m/m)(Nturn)

2 4 6 8 10 12 14 16 18

Time-of-Flight / ms

MR-TOF-MS: Mass Resolving Power

133Cs+, Ion kinetic energy 1.3 keV 2 turn 2 turn turn

) ( 2 ) ( / T N T T T N N m m         

m/m = 450,000 m/m = 100,000 54 turns 2 ms

~10-7 up to 70% ~10 ions World-wide unique combination of performance characteristics! >106 ions/s

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SLIDE 9
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

MR-TOF MS Buncher / Degrader Stopping Cell

FRS Ion Catcher a Test Facility for the LEB

In-flight Production In-flight Separation Momentum Compression Stopping / Thermalization

Target Fragment Separator Primary Beam

100...1500 MeV/u ~ eV ~ keV ~ MeV/u Isobar Separation SuperFRS LEB Experiments (Trap, Laser,..) MATS / LaSpec

W.R. Plaß et al., NIM B 317 (2013) 457

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SLIDE 10
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Setup at the FRS Ion Catcher at GSI

Cryogenic Stopping Cell Diagnostics Unit Time-of-Flight Mass Spectrometer Cooling System

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SLIDE 11
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Systematic Investigations

2 4 6 8 0.0 0.5 1.0 1.5

Normalized Counts Time / d

2 4 6 8 10 10 20 30 40

calculated for max DC field using mobility theory measurments using pulsed 223Ra source

mean extraction time (ms) area density (mg/cm^2)

Extraction time:

  • Extraction time independent
  • f areal density
  • given by mechanical desgin
  • f stopping cell

Stability of operation:

from production to mass measurement

Stable over one week beam time

213Fr measured with MR-TOF-MS

in High Resolution mode

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SLIDE 12
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Improved Total Efficiency

  • Carpet with improved electrical desgin:
  • Higher RF-amplitude possible and lower temperatures
  • Improved bake-out + New carpet

 better cleanliness  Higher ion survial and extraction efficiency (eg. 223Th)

  • Higher differential pumping

 Higher areal density  Higher stopping efficiency 2012: 3.1 mg / cm² 2014: 6.3 mg / cm²  Improved total efficiency up to 30% Factor 2 higher than 2012

Year

  • Max. RF-amplitude

Temperature of RF coil 2012 80 Vpp 270 °K 2014 140 Vpp 150 °K

2011 2012 2013 2014 50 100

Ion survival and extraction efficiency / % Year of experiment

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SLIDE 13
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

30 32 34 36 38 40 42 44 46 48 50 1 10 100

124Xe + 131Xe + + 129Xe +

Counts TOF-4,528.83 µs (µs)

220Ra 2+

SF

+ 4

SF

+ 5

SF

+ 4

SF

+ 5 136Xe + 134Xe + 124Xe +

SF

+ 5 124Xe + 128Xe + 132Xe +

110,002 110,004 110,006 110,008 2 4 6

Counts

mass-to-charge / (u/e) Data Gaussian Fit

220Ra 2+

Half-life: 17.9 ms 11 ions

Mass Measurement: Uranium Projectile Fragments

  • Mass window of ~ 30 u
  • Mass resolving power ~ 120,000
  • Doubly charged
  • Shortest half-life
  • Highest sensitivity
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SLIDE 14
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

7100 7150 7200 7250 7300 7350 7400 7450 7500 0,000 0,025 0,050 0,00 0,05 0,10

counts / s

energy / keV

Gate on Gate off 211mPo 211Po

Spatial separation of ground state and isomeric state Measurement of isomers

  • Identification of 211Po and 211mPo
  • Measurement of excitation energy
  • Measurement of isomeric ratio
  • Separation using the

ion gate of the MR-TOF-MS

  • Proof-of-principle:

production of isomerically clean beams

211mPo 210.980 210.985 210.990 5 10 15 20

211Po

Abundance Mass-to-Charge Ratio / (u/e)

211mPo

211mPo 211Po

m/m = 250,000

1.5 MeV

Isomeric Beams Measurement and Separation of Isomers

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SLIDE 15
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

132.904 132.906 132.908 132.910 10 100

Counts Mass-to-Charge / (u/e)

1.6 MeV

m/m = 360,000

Mass Measurement: Uranium Fission Fragments

0.3 MeV

  • Mass measurement of uranium fission products produced at 1000 MeV/u
  • MR-TOF-MS will enable efficient search and measurement of new

isotopes and isomers

133Cs 133mI 133I 133Te 133mTe

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SLIDE 16
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

FRS identification may not always be accurate (need to identify one isotope in the identification plot)  MR-TOF-MS as mass tagger  helped to correctly identify 134I Universal and fast technique (~20 min)

134I

CSC + MR-TOF-MS as Mass Tagger

Z-calibration of by 3,5e A from A/Q of by 8 u/e 134I

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SLIDE 17
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Conclusions and Outlook

(Prototype)Stopping cell for the Super-FRS and the FRS Ion Catcher

  • Cryogenic, high density operation, suitable for

exotic nuclei produced at relativistic energies

  • Unprecedented efficiencies for relativistic ions

Access to short life times (extraction time ~ 25 ms) High-performance multiple-reflection time-of-flight mass spectrometer

  • High-accuracy mass measurements at m/m up to ~ 450,000

Harvest of 6 shifts of beam time:  8 first direct mass measurements, e.g. 220Ra (T1/2 = 17.9 ms, 11 ions only)

  • Powerful tool for the measurement of isomers:

Identification, excitation energies, isomeric ratios

  • High-resolution mass separator for isobars and isomers
  • Diagnostics tool: identification and quantification

Development of the future stopping cell for the Super-FRS

  • Higher areal densities
  • Shorter extraction times
  • Higher rate capabilities
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SLIDE 18
  • T. Dickel, Results from the FRS Ion Catcher with projectile and fission fragments, NUSTAR Annual Meeting, Darmstadt/GSI, March 2 – 6, 2015

Acknowledgements

Funding: BMBF (06GI185I, 06GI9114I, 05P12RGFN8), State of Hesse (HMWK) (LOEWE Center HICforFAIR),

  • Univ. Groningen and GSI,

JLU Giessen and GSI (JLU-GSI strategic Helmholtz partnership agreement)

FRS Ion Catcher / S411 Collaboration

  • F. Amjad2, S. Ayet2, T. Dickel1,2, P. Dendooven3, M. Diwisch1,
  • J. Ebert1, A. Estrade2, F. Farinon2, H. Geissel1,2, F. Greiner1,
  • E. Haettner1, F.Heiße2, C.Hornung1, C. Jesch1, N. Kalantar-

Nayestanaki3, R. Knoebel2, J. Kurcewicz2, J. Lang1, W.Lippert1, I. Miskun2, I. Moore4, C. Nociforo2, A. Pikhtelev5,

  • M. Petrick1, M. Pfuetzner2, W.R. Plaß1,2, S. Pietri2, I.

Pohjalainen4, A. Prochazka2, S. Purushothaman2,

  • M. Ranjan3, M.P. Reiter1, A.-K. Rink1, S. Rinta-Antila4,
  • C. Scheidenberger2, M. Takechi2, Y. Tanaka2, H. Weick2,

J.S. Winfield2, X.Xiaodong1,2, M.I. Yavor6

1 II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen, Germany 2 GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany 3 KVI, University of Groningen, The Netherlands 4 University of Jyväskylä, Jyväskylä, Finland 5 Institute for Energy Problems of Chemical Physics, RAS, Chernogolovka, Russia 6 Institute for Analytical Instrumentation, RAS, St. Petersburg, Russia